Reusable, outwardly tapered frames for air filters

Abstract

Reusable frames for air filters, framed air filters, kits for making framed air filters, and methods of making and using framed air filters. The frame may be a channel frame in which each frame portion of the frame includes an outer sidewall and an upper flange and a lower flange. The channel frame may be outwardly tapered so as to exhibit an outward taper ratio.

Description

[0001] PA103293W002

[0002] REUSABLE, OUTWARDLY TAPERED FRAMES FOR AIR FILTERS Background

[0003] Air filters are commonly used in powered air-handling apparatus, e.g. residential and commercial

[0004] 5 heating and air-conditioning (HVAC) systems, room air purifiers, and so on, in order to remove dust and dirt particles, fine particulates and so on. Conventional air filters have permanent rigid frames that dictate that the air filter must exhibit its in-use size when shipped to a retailer, when presented to potential purchasers, and when stored by an end-user. Consequently, these air filters undesirably occupy a relatively large volume of space on transportation vehicles, on retailer shelves, and in end-user’s homes.

[0005] Summary

[0006] Disclosed herein are reusable frames for air filters, framed air filters, kits for making framed air filters, and methods of making and using framed air filters. In one aspect, such a reusable frame may include a lower base and a upper cover that are detachably attachable to each other to form the frame. In another aspect, the reusable frame may be a channel frame in which each frame portion of the frame comprises an

[0007] 15 outer sidewall and an upper flange and a lower flange. In another aspect, the frame may be outwardly tapered so as to exhibit an outward taper ratio. These and other aspects will be apparent from the detailed description below. In no event, however, should the above summaries be construed as limitations on the claimed subject matter, which subject matter is defined solely by the attached claims, as may be amended during prosecution.

[0008] 20 Brief Description of the Drawings

[0009] FIG. 1 is a perspective view, from an upward side, of an exemplary pleated air filter installed in an exemplary reusable outwardly tapered frame to form a framed air filter.

[0010] FIG. 2 is a perspective view, from an upward side, of the exemplary frame of FIG. 1, in the absence of a pleated air filter.

[0011] 25 FIG. 3 is a perspective view, from an upward side, of the exemplary frame of FIG. 2, with an upper cover and a lower base of the frame shown exploded apart from each other.

[0012] FIG. 4 is a perspective view of the exploded-apart upper cover and lower base of FIG. 3, viewed from a downward side.

[0013] FIG. 5 is a cross-sectional view of the exemplary frame of FIG. 2, taken generally along line 5-5 of FIG. 2.

[0014] FIG. 6 is a cross-sectional view of the exemplary frame of FIG. 2, taken generally along line 6-6 of FIG. 2.

[0015] FIG. 7 is a perspective view, from an upward side, of the exemplary pleated air filter of FIG. 1.

[0016] FIG. 8 is a side -perspective view of a primary end portion of the exemplary pleated air filter of

[0017] 35 FIG. 7. FIG. 9 is a cross-sectional view of a portion of the exemplary framed air filter of FIG. 1, taken generally along line 9-9 of FIG. 1, and with the items therein being exploded apart from each other in an upward-downward direction.

[0018] FIG. 10 is a perspective view, from an upward side, of a portion of an exemplary pleated air filter as installed in an exemplary lower base of a reusable frame.

[0019] FIG. 11 is a perspective view, generally from the downward side, of an exemplary upper cover of a reusable frame.

[0020] FIG. 12 is a perspective view, generally from the upward side, of an exemplary lower base of a reusable frame.

[0021] Some background features have been omitted from the cross-sectional views of FIGS. 5, 6 and 9, in order that features at the cross-sectional cutting location can be seen more easily. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated. Like reference numbers in the various figures indicate like elements. Some elements (e.g. primary portions of a rectangular frame, and secondary portions of the frame, and various components thereof), may be present as multiples that are similar or identical except for their position and / or orientation). Some such elements may be labeled as “first” and “second” by way of “F” and “S” subscripts as evident in various Figures.

[0022] As used herein as a modifier to a property, attribute or relationship, the term “generally”, unless otherwise specifically defined, means that the property, attribute or relationship would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties). The term “substantially” means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties) but again without requiring absolute precision or a perfect match. The term “configured to” and like terms is at least as restrictive as the term “adapted to”, and requires actual design intention to perform the specified function rather than mere capability of performing such a function. The term “integral” denotes items that are portions of the same overall entity, are of the same composition, and that were made concurrently in the same manufacturing process, e.g. by injection molding.

[0023] Terms such as “outer”, “outward”, “outwardmost”, “outwardly”, and the like, refer to a direction generally away from the geometric center of an air filter, a frame for an air filter, and a framed air filter. Terms such as “inner”, “inward”, “inwardmost”, “inwardly”, and the like, refer to a direction generally toward the geometric center. The term “upward” and like terminology are defined as the direction that the open ends of open-ended elongate slots of a frame generally face, as discussed in detail later herein. The term “downward” and similar terms denote an opposing direction. Various Figures are marked with “U” and “D” to aid in recognition of upward and downward directions. This terminology is used in view of the fact that in many embodiments, a lower base that is to receive an air filter will be placed on a horizontal surface (e.g. a tabletop or countertop) with the open ends of the elongate slots facing up as discussed later herein. This terminology is used for ease of description and does not limit the orientation that a framed air filter can be placed in, e.g. when it is installed into a receptacle of a powered air-handling apparatus.

[0024] The term “upstream” is used to denote a side of a framed air filter (and a frame and air filter thereof) upon which, with the framed air filter installed in a powered air-handling apparatus, moving air will impinge on the framed air filter to be filtered thereby. The term “downstream” is used to denote the side of such items from which filtered air will exit the framed air filter. In many embodiments (e.g. in a “standard” installation as discussed later herein) the upward side of a framed air filter may correspond to the upstream side of the framed air filter as installed in a powered air-handling apparatus, with the downward side of the framed air filter similarly corresponding to the downstream side as installed in the powered air-handling apparatus. However, in some embodiments (e.g. in a “reverse” installation as discussed later herein) this may not be the case.

[0025] Detailed Description

[0026] Shown in FIG. 1 in perspective view generally from the upward side is an exemplary framed air filter 1 as disclosed herein. Framed air filter 1 comprises a pleated air filter 400 installed in a reusable frame 10. In many embodiments, pleated air filter 400, frame 10, and framed air filter 1, will all be at least generally rectangular in shape (which specifically includes square shapes). As evident from FIG. 2, frame 10 may thus take a rectangular form with four major elongate frame portions in two opposing pairs. One pair of opposing frame portions will be termed primary portions 12 and another pair of opposing frame portions will be termed secondary portions 13, with the primary and secondary portions meeting at frame comers 14. The resulting framed air filter will similarly comprise two primary portions 2 and two secondary portions 3, and four comers 4. In some Figures herein, such first and second opposing primary portions are labeled 2Fand 2s; first and second opposing secondary portions are similarly labeled 3Fand 3s. Other items and components of frame 10, pleated air filter 400, and framed air filter 1 that are present in pairs (or, in general, in multiples) may be similarly labeled and / or referred to herein. Here and elsewhere, the terminology of first and second is for convenience of description and does not imply any classification as to function or order, unless specifically noted.

[0027] Frame 10 is reusable and is configured to define a filter-receiving cavity 30 that accepts a pleated air filter 400 therein. As depicted in FIG. 7, pleated air filter 400 comprises first and second opposing primary ends 402Fand 402s that are non-corrugated ends and that respectively comprise first and second securing tabs 501Fand 501 s. Pleated filter 400 also comprises first and second opposing secondary edges 403Fand 403s that are corrugated edges, as discussed in detail later herein. In many embodiments, air filter 400 will be pleated so as to exhibit a pleat direction (denoted as Dpin various Figures) that is aligned with the long axis of the pleats. In some embodiments, air filter 400 will be expandable along an expansion direction (denoted as De) in various Figures. The securing tabs 501 of primary ends 402 of pleated air filter 400 are insertable into upward-open- ended elongate slots 260 (visible in various Figures herein) of frame 10 in order to install air filter 400 into frame 10. The primary portions 12 of frame 10 are those that comprise upward-open-ended elongate slots 260 and to which the primary ends 402 of air filter 400 are attached; the secondary portions 13 of frame 10 are those along which the secondary, corrugated edges 403 of the air filter are positioned. Frame 10 (and the resulting framed air filter 1) will have a primary direction and axis that is parallel to primary portions 12 of frame 10; and, a secondary direction and axis that is parallel to secondary portions 13 of frame 10; primary direction / axis P and secondary direction / axis S are denoted in various Figures. In some embodiments, the pleat direction Dpof the air filter will be aligned with the primary axis P of frame 10 and the expansion direction Deof the air filter will be aligned with the secondary axis S of frame 10, as evident in FIG. 1.

[0028] As evident e.g. from FIGS. 2-4, in the depicted embodiment, frame 10 is comprised of two major frame pieces 210 and 110 that are assembled together with air filter 400 therein to form framed air filter 1. Frame piece 210 will be referred to herein as a lower base; frame piece 110 will be referred to herein as an upper cover. Frame 10, as made by joining lower base 210 and upper cover 110, will define a filterreceiving cavity 30 that is configured to receive pleated air filter 400. In some embodiments, lower base 210 and upper cover 110 may be similar or nearly equal in size and height (as in the exemplary design of FIGS. 1-4), e.g. so that the height (along the upward-downward axis) of upper cover 110 is within 30, 20, 10, or 5 % of the height of lower base 210.

[0029] A frame 10 as disclosed herein is a channel frame, by which is meant a frame whose primary portions and secondary portions each exhibit a generally U-shaped appearance when viewed in crosssection. A primary frame portion 12 of such a channel frame will generally comprise an outer sidewall 22 (the “base” of the “U”) and an upper flange 24 and a lower flange 26 (the “arms” of the “U”) as shown in FIG. 5; a secondary frame portion will similarly comprise an outer sidewall 23 and an upper flange 25 and a lower flange 27 as shown in FIG. 6. In the depicted embodiment of FIG. 5, the outer sidewall 22 and the upper flange 24 of primary frame portion 12 are provided by outer sidewall 122 and upper flange 124 of a primary portion 112 of upper cover 110. Similarly, in the depicted embodiment of FIG. 6, the outer sidewall 23 and the upper flange 25 of secondary frame portion 13 are provided by outer sidewall 123 and upper flange 125 of a secondary frame portion 113 of upper cover 110. In the depicted embodiment, all of these outer sidewalls and upper flanges (and all of the primary and secondary portions of upper cover 110) are integral parts of upper cover 110. In the depicted embodiment, the lower flange 26 of primary frame portion 12 is provided by a lower flange 226 of a primary portion 212 of lower base 210 ; similarly , the lower flange 27 of secondary frame portion 13 is provided by a lower flange 227 of a secondary portion 213 of lower base 210. These lowerflanges (and all of the primary and secondary portions of lowerbase 210) are integral parts of lower base 210. Outwardly Tapered Channel Frame

[0030] As noted, the herein-disclosed frame is a channel frame whose primary portions and secondary portions each externally exhibit a generally U-shaped appearance when viewed in cross-section. In further detail, each frame portion of a channel frame will comprise first and second flanges (that are configured to be upstream and downstream flanges, when the frame is installed in a powered air-handling apparatus) that are spaced apart a distance at least generally corresponding to the pleat height (as defined later herein) of a pleated air filter that is installed in the channel frame. By definition, a channel frame will be distinguished from a type of frame often referred to as a “pinch” frame. Each portion of a pinch frame will comprise upstream and downstream flanges that are very close together (e.g. within 5, 3 or 1 mm of each other) with an edge of the air filter that is installed in the frame, being firmly captured (e.g., “pinched”) between the two closely-spaced flanges. In the case of an air filter that is pleated, the space between the upstream and downstream flanges of the pinch frame will be much less than the pleat height, so that the pleats at the corrugated edges of the pleated air filter are typically cmshed or crumpled between the flanges. Although some pinch frames may comprise one or more walls that are sloped (e.g. to promote nestability), this will not provide an outwardly tapered channel frame as disclosed herein.

[0031] Examples of frames that fall into the general category of pinch frames and that thus do not qualify as an outwardly tapered channel frame as disclosed herein, include the frames disclosed in U.S. Patents 7537632, 8702829, 9174159, 9278301, 9962640, 10328378, 11179665 and 11376537, and in U.S. Patent Application Publications US / 20240207769 and US2024 / 0181377. Examples of frames that have various designs that do not qualify as an outwardly tapered channel frame as disclosed herein include the frames disclosed in U. S. Patents 6126707, 8979966, and 10744441. Examples of frames that do fall into the general category of channel frames (although not being outwardly tapered in the manner of the herein-disclosed frame) include the frames disclosed in U.S. Patents 7622063, 8142538, 11253807 and 11697088, and in PCT Patent Application Publication WO2024 / 105488.

[0032] Frame 10 as disclosed herein is outwardly tapered. By this is meant that the two opposing primary portions 12 of frame 10, and the two opposing secondary portions 13 of frame 10, are all outwardly tapered as respectively illustrated in FIGS. 5 and 6. By outwardly tapered is meant that the height (along the upward-downward direction) of an outermost surface of the outer sidewall of the frame portion, is less than the height of an inwardmost section of the frame portion. For the exemplary primary frame portion 12 shown in FIG. 5, this is illustrated by height 141 of the outermost surface 128 of the outer sidewall 22 of primary frame portion 12, which is less than the height 142 of an inwardmost section 135 of primary frame portion 12. Similar definitions and characterizations apply to the secondary frame portion 13 shown in FIG. 6.

[0033] This outward taper can be quantified in terms of an outward taper ratio, which is the ratio of the height of the outermost surface to the height of the inwardmost section (in FIG. 5, the ratio of height 141 to height 142). By definition, an outwardly tapered frame portion will exhibit an outward taper ratio of at most 0.95. In various embodiments, an outward taper ratio of a frame portion may be at most 0.90, 0.85, 0.80, 0.75, or 0.70. In further embodiments, such an outward taper ratio may be at least 0.60, 0.65, 0.70, or 0.75. (By way of a specific example, the exemplary frame portion shown in FIG. 5 exhibits an outward taper ratio of approximately 0.80.)

[0034] Frame 10 is tapered as the result of the discovery of a problem. Framed air filters are often installed in filter-receptacles provided in an HVAC system e.g. of a residential house. Such a filter-receptacle of an HVAC system typically comprises a fixture (often in the form of a set of flanges). This framed-air-filter- holding fixture (and, in particular, an access slot through which the framed air filter is inserted in the act of installing the framed air filter in the HVAC fixture), are often provided in the ducting (e.g., return-air ducting) of the HVAC system. The formation of such fixtures and access slots is often performed onsite, and typically involves manual manipulation of sheet metal (e.g. cutting, bending, folding, forming of seams and joints, etc.). The present investigations have revealed that such manipulations often result in significant variation in the dimensions of the access slot and / or the framed-air-filter-holding fixture. Field investigations have revealed that fixtures and access slots that are nominally sized to accommodate a 1- inch framed air filter can range from e.g. 0.90 inches to 1.1 inches in size (in the upstream-downstream direction). Such variation, in particular when the actual size of the access slot is somewhat less than the nominal (intended) size of the access slot, can cause difficulty in slidably inserting a framed filter through the access slot into the holding fixture. These problems can be exacerbated if the access slot (or any flange of the holding fixture) has any rough edges, burrs, etc.

[0035] Such a problem might be addressed by providing a framed air filter that has a reduced height (e.g. 0.90 inches) throughout the entire length and width of the framed filter, in order to ensure that the framed air filter can be inserted even into access slots and fixtures that are slightly smaller than a nominal, intended size (of e.g. 1 inch). However, such arrangements will likely require that the pleat height of the pleated air filter of the framed filter be reduced accordingly. This reduces the surface area of the air filter media that is available for filtration, with commensurate reduction in filtration performance. The present investigations have revealed that using an outwardly tapered channel frame as disclosed herein can enhance the ease of slidably inserting the framed air filter into a receptacle of an HVAC system, while mitigating, or even totally avoiding, any need to reduce the pleat height of the pleated air filter media. Specifically, the reduced “height” of the outermost face of the frame (e.g., height 141 of outermost surface 128 as depicted in FIG. 5) can make it easier to initiate the insertion of the frame into an access slot. Once this narrowest leading edge of the frame has entered the access slot, the slidable insertion can be continued. If the access slot is indeed narrower than normal, a greater-height section of the frame (e.g. moderately-sloped inward section 133 of upper flange 24 of FIG. 5) may contact on an edge of the slot. However, this contact will occur at a glancing angle that does not unduly interfere with the ability to continue slidably moving the framed air filter through the access slot and into the holding fixture of the HVAC system. The materials of which the frame portions (and sections thereof) are made, and the thicknesses of various components of the frame portions, can be chosen to facilitate the above arrangements. For example, in some embodiments at least the upper cover 110 of reusable frame 10 may be made of a thermoplastic organic molding resin such as acrylonitrile-butadiene-styrene, polyamide, polyoxymethylene, polypropylene, etc. Also, the various components of each frame portion of the upper cover (in particular, a sloped component such as upper flange 24) may be configured to have a suitably chosen thickness of e.g. 1.0 - 3.5 mm in the upward-downward direction. This combination of material properties and component thickness can provide that certain components of a frame portion (e.g. an upper flange 24) will be at least slightly deflectable. This deflectability will provide that one or more flanges can be at least slightly deflected inward (along the upward-downward direction) as the frame portion passes into and / or through the access slot. This will allow the frame portion to successfully pass through the access slot in a manner that might not be possible if the channel frame were to be made of a very rigid material such as e.g. sheet metal.

[0036] In some embodiments, the above-discussed arrangements can be enhanced by providing a frame portion with variable taper; specifically, in which the slope is rather steep in the outermost section of the frame portion and decreases toward the inwardmost section of the frame portion. Such an arrangement is exhibited in exemplary embodiment with the primary frame portion 12 shown in FIG. 5. In the depicted embodiment, the outer sidewall 22 of the primary frame portion 12 (which is provided by an outer sidewall 122 of a primary portion 112 of upper cover 110) comprises a planar outermost surface 128 that is oriented in the upward-downward direction. The orientation of surface 128 and related surfaces will be characterized by a slope angle, which is defined as the angle between the surface and a plane that is perpendicular to the upward-downward direction (in other words, a plane that coincides with the primary and secondary axes of the framed air filter). For outermost surface 128, the slope angle is 90 degrees. Adjacent to outermost surface 128, and extending integrally therefrom, is an outward sloped section 131 that exhibits a slope angle (denoted by reference number 143) of approximately 45 degrees. Extending integrally from an inward end 132 of outward sloped section 131, is an inward sloped section 133 that exhibits a slope angle (denoted by reference number 144) of approximately 15 degrees. Extending integrally from an inward end 134 of inward sloped section 133, is an inwardmost section 135 that is substantially unsloped (meaning that it exhibits a slope angle of less than 5 degrees).

[0037] An arrangement as discussed above will be referred to herein as exhibiting compound taper, meaning that a frame portion comprises at least two sloped sections (not counting an outermost surface that has a slope angle of 90 degrees, and not counting a substantially unsloped inwardmost section) that have slope angles that differ by at least 10 degrees. Any such section with the highest slope angle (e.g., an outward, often an outermost, sloped section 131) will be termed a highly-sloped section, with a section with a lesser slope angle (e.g., inward sloped section 133 of FIG. 5) then being termed a moderately-sloped section. The terms highly-sloped and moderately-sloped are thus used in a relative sense to mean that the moderately-sloped section exhibits a slope angle that is less than that of the highly-sloped section by at least 10 degrees.

[0038] In various embodiments, a highly-sloped section can exhibit a slope angle of at least 25, 30, 35, or 40 degrees; in further embodiments, the highly-sloped section can exhibit a slope angle of at most 80, 70, 60, or 50 degrees. By way of a specific example, the slope angle 143 of highly-sloped section 131 of FIG. 5, is approximately 45 degrees. In various embodiments, a moderately -sloped section can exhibit a slope angle of at least 5, 8, 11, or 14 degrees; in further embodiments, the moderately-sloped section can exhibit a slope angle of at most 20, 18, or 16 degrees. By way of a specific example, the slope angle 144 of moderately-sloped section 133 of FIG. 5, is approximately 12 degrees.

[0039] Sections of a compound-tapered frame portion can be additionally characterized in terms of the “span” of each section, and the ratio of such spans. The “span” of a section of a primary frame portion 12 is the length of the section along its secondary axis S, as evident from FIG. 5. The span of highly-sloped outward section 131 is identified in FIG. 5 by reference number 145; the span of moderately-sloped inward section 133 is identified by reference number 146. In various embodiments, the span of a moderately-sloped section can range from at least 5, 7 or 9, to at most 20, 17, 14, and 11, times the span of a highly-sloped section. By way of a specific example, in the exemplary arrangement shown in FIG. 5, the ratio of span 146 of moderately-sloped section 133 to the span 145 of highly-sloped section 131 is approximately 7.)

[0040] In some embodiments, a frame portion may exhibit asymmetric taper, meaning that a lower flange of the frame portion is not tapered in the same manner as the upper flange of the frame portion. (In other words, when the frame portion is in side view as in FIG. 5, the tapered sections of the lower flange will not be mirror images of the tapered sections of the upper flange.) This is the case with primary frame portion 12 as shown in FIG. 5. As discussed above, upper flange 24 exhibits compound taper, with an outward, highly-sloped section 131 and an inward, moderately-sloped section 133 (in addition to an inwardmost, substantially unsloped section 135). Lower flange 26, in contrast, does have an outward, highly-sloped section 231 but does not have an inward, moderately-sloped section. Instead, the inward end 232 of highly- sloped section 231 is integrally, directly connected to a substantially unsloped section 235. Such an arrangement will be referred to as exhibiting single taper. Discussions later herein will make it clear that the use of asymmetric taper, in particular, a design in which an upstream flange (as installed in an HVAC system) exhibits greater taper than a downstream flange, can allow the advantages presented herein to be realized, while also providing other useful results. For example, the use of lower flanges whose only sloped sections are highly-sloped outward sections can allow certain downstream surfaces (as installed in an HVAC system) of the lower flanges to beneficially provide a sealing apron 284 as discussed elsewhere herein.

[0041] It will be apparent from FIG. 5 that in the depicted arrangement, the outer sidewall 22 and its planar outermost surface 128, the highly-sloped outward section 131, the moderately-sloped inward section 133, and the substantially unsloped inwardmost section 135, are all provided by respective features of upper cover 110. The other highly-sloped outward section 231, as well as substantially unsloped inward section 235, are provided by a lower flange 226 of lower base 210. A slope angle can be calculated for the highly- sloped outward section 231 of lower flange 226 in similar manner as discussed above. In the depicted embodiment, highly-sloped outward section 231, and highly-sloped outward section 131, are symmetrical (mirror images of each other) and exhibit nearly -identical slope angles (of opposite orientation).

[0042] Discussions so far have focused on the exemplary primary frame portion 12 depicted in FIG. 5. Similar arrangements are shown in FIG. 6 for an exemplary secondary frame portion 13. That is, secondary frame portion 13 is asymmetrically tapered, with upper flange 25 exhibiting compound taper and with lower flange 27 exhibiting single taper. Highly-sloped outward section 131s and highly-sloped outward section 231s of secondary frame portion 13 exhibit slope angles that are very similar to their counterparts of primary frame portion 12; the same is true of substantially-unsloped inwardmost sections 135s and 235s in relation to their counterparts of primary frame portion 12.

[0043] One difference between secondary frame portion 13 as shown in FIG. 6 and primary frame portion

[0044] 12 as shown in FIG. 5 is that the span of moderately -tapered inward section 133s of upper flange 25 of the secondary frame portion 13 of FIG. 6, is noticeably larger than the span of the moderately-sloped inward section 133 of upper flange 24 of the primary frame portion 12 of FIG. 5. (In the depicted embodiment of FIG. 6, the ratio of span 146s of moderately-sloped section 133s, to the span 145s of highly-sloped section

[0045] 13 Is, is approximately 10.) Also, moderately-sloped section 133s of secondary frame portion 13 has a slope angle that, while not specifically denoted in FIG. 6, can be seen to be slightly smaller then the slope angle 144 of moderately-sloped section 133 of primary frame portion 12. Reasons for these differences will be discussed later herein.

[0046] Regardless of these variations, it will be appreciated that it is advantageous to provide outward tapering on both primary frame portions 12 and secondary frame portions 13 of frame 10. This is needed because some HVAC filter-receptacles are configured so that a framed air filter is installed therein by slidably moving the framed filter along its primary axis, while other HVAC filter-receptacles are configured so that a framed air filter is installed therein by slidably moving the framed filter along its secondary axis. Also, each of the opposing primary frame portions, and each of the opposing secondary frame portions, should be tapered, since in many cases a framed air filter can be installed by moving it in either direction along its primary axis, or in either direction along its secondary axis. This being the case, in many embodiments all four frame portions will be configured to exhibit outward tapering as disclosed herein.

[0047] Variations of the above-described arrangements are possible. For example, the above-described frame portions exhibit variable taper (e.g., compound taper) by way of comprising a generally polygonal profile comprising two or more generally planar sections (e.g. chamfers or bevels) that meet at one or more junctions at which a relatively abrupt change in slope is present (as with sections 131 and 133 that meet at junction 132, and sections 135 and 133 that meet at junction 134, in FIG. 5). In some embodiments, a frame portion may exhibit variable taper by way of exhibiting a generally arcuate profile that exhibits a slope angle that smoothly decreases from a high value at the outwardmost section of the profiled frame portion, to a lower value at an inward section of the profiled frame portion. In some such embodiments, the frame portion may nevertheless still comprise a sidewall with a generally planar outermost surface (e.g., similar to outermost surface 128 as shown in FIG. 5) and / or may still comprise a substantially-unsloped inwardmost section (e.g., similar to inwardmost section 135 as shown in FIG. 5). Combinations of these general designs are possible, e.g. a frame portion include generally planar sections and smoothly curved sections. Also, although various numerical examples are presented herein with reference to a framed air filter with a nominal height / depth (corresponding to the upstream-downstream direction when installed in a powered air-handling apparatus) of e.g. 1 inch, the arrangements disclosed herein can be used with any framed filter. For example, such arrangements may be used with so-called “deep pleat” filters that have a nominal height / depth of 4 inches.

[0048] Struts

[0049] As shown in FIGS. 3 and 4, lower base 210 will define a lower window 217 that allows flowing air to pass therethrough. In a standard installation of framed air filter 1 in an HVAC filter-receptacle, air that exits the pleated air filter 400 will pass through window 217. In some embodiments, lower base 210 will comprise a lower lattice collectively provided by lower struts 293 and 294 that extend over at least a portion of lower window 217. Often, such lower struts will be integral with the primary portions 212, and / or the secondary portions 213, of lower base 210. In some such embodiments, such a strut-lattice, being downstream of pleated air filter 400 (again, in a standard installation in an HVAC filter-receptacle), can support the pleated air filter 400 against the pressure developed by the moving air impinging on the air filter 400. (In other words, the lower struts may serve to prevent pleated air filter 400 from billowing or otherwise deforming in the downstream direction due to the air pressure).

[0050] Likewise as shown in FIGS. 3 and 4, upper cover 110 will define an upper window 117 that allows flowing air to pass therethrough. In some embodiments, upper window will be collectively defined by inwardmost edges 136 of upper flanges 24 of primary portions 112 of upper cover 110 and inwardmost edges 136s of upper flanges 25 of secondary portions 113 of upper cover 110, as seen respectively in FIGS. 5 and 6. In a standard installation of framed air filter 1 in an HVAC filter-receptacle, incoming (return) air will pass through window 117 in order to enter pleated air filter 400 to be filtered thereby. In some embodiments, upper cover 110 will comprise an upper lattice collectively provided by upper struts 193 and 194 that extend over at least a portion of upper window 117. Often, such upper stmts will be integral with the primary and / or secondary portions of the upper cover. Such upper struts, if present, may be similar in appearance to lower struts 293 and / or 294 and / or may be similarly oriented and positioned. Such upper struts may not be needed to support the pleated air filter if the framed air filter 1 is installed in a receptacle of a powered air-handling apparatus in a standard configuration. However, such upper struts may enhance the overall mechanical robustness of the frame (without unduly reducing the previously-discussed “deflectability” of certain components of the frame). Also, in some embodiments, such upper struts may support the pleated air filter if the framed air filter is installed in a receptacle of a powered air-handling apparatus in a “reverse” configuration as discussed later herein.

[0051] In some embodiments, lower struts 293 / 294, and upper struts 193 / 194 (if present), can be configured to preserve or enhance, the ability to slidably insert framed air filter 1 into a filter-receptacle of an HVAC system. Specifically, any or all such struts can be oriented so that the long axis of the strut is not oriented perpendicular to the direction of slidable insertion of the framed air filter into the filter-receptacle. It will be appreciated that if a strut is oriented perpendicular (or nearly -perpendicular) to the direction of slidable insertion, this can increase the possibility of a leading edge of the strut becoming snagged on some component of the filter-receptacle of the HVAC system. Often, the previously -described access slot through which the framed air filter is slidably inserted into the filter-receptacle, is the narrowest bottleneck that is encountered during the insertion; thus, a leading edge of a strut may snag on an edge of the access slot.

[0052] The present investigations have revealed that orienting struts at an offset angle relative to the direction of slidably insertion of the framed air filter into a filter-receptacle of an HVAC system, can minimize or substantially eliminate any such strut-snagging. However, as mentioned previously, different HVAC systems have filter-receptacles that require different directions of filter-insertion (e.g., along the primary axis of the framed air filter, or along the secondary axis of the framed air filter). Accordingly, the present investigations have revealed that it can be advantageous to orient the struts at an off-angle that is intermediate between the primary and secondary axes of the frame.

[0053] One such exemplary arrangement of strut angles is visible in FIGS. 1-4, with the arrangements being similar for upper struts 193 of upper cover 110 and for lower struts 293 of lower base 210. With reference to lower base 210 as shown in FIG. 3 , such strut-orientation arrangements can be quantified with reference to a central 50 % of window 217 of the lower base 210. By a central 50 % is meant an area that occupies 50 % of the total area of window 217 and that has borders that are complementary to those of window 217. An exemplary central 50 % of window 217 is indicated by dashed-lines 218 in FIG. 3.

[0054] In some embodiments, within this central 50 % of a window of a lower base, all of the lower struts 293 and 294 of lower base 210 will be oriented at an off-angle of from 35 degrees to 75 degrees relative to the primary axis P of the lower base. By way of a specific example, the exemplary struts 293 of lower base 210 of FIG. 3 are oriented at an off-angle of approximately 45 degrees relative to primary axis P (and are likewise oriented at an off-angle of approximately 45 degrees relative to secondary axis S). Similar arrangements are provided for exemplary struts 193 of upper cover 110 of FIG. 3.

[0055] It will be noted that in the exemplary arrangement of FIG. 3, lower struts 294 of lower base 210 and upper struts 194 of upper cover 110 deviate from the orientation of struts 293 and 193 (and are oriented at off-angles of approximately 70 degrees to the primary axis P). This is an optional arrangement that ensures that no strut directly crosses the geographic center (centroid) of the framed air filter. Such an arrangement may be used if it is desired to position a sensor (e.g. an airflow sensor, for purposes of monitoring the remaining filter life) on the framed filter, the geographic center often being an optimum place to position such a sensor. Many arrangements of this general type are possible, some of which can position one or more struts close to the geographic center, e.g. so that a sensor may be supported by the strut(s), but without the strut(s) crossing directly over the geographic center.

[0056] Other features may enhance the ability of a framed air filter 1 to be slidably inserted into an HVAC filter-receptacle. As noted, frame 10 will have four comers 4; upper cover 110 will similarly have four comers 114 and lower base 210 will similarly have four comers 214. As evident e.g. from FIGS. 2 and 3, at the four comers 4 of frame 10, the outer sidewalls of upper cover 110 at the four comers 114 of upper cover 110, will provide the outer sidewalls of frame 10. At comers 114 of upper cover 110, each of these outer sidewalls can be rounded for ease of inserting frame 10 through an access slot and into an HVAC filter-receptacle. Thus in various embodiments, the outer sidewalls of upper cover 110 at the four comers 114 of upper cover 110, may be arcuate so as to exhibit a radius of curvature (when viewed along the upward-downward direction) of e.g. from 1 to 3 cm. By way of a specific example, the exemplary upper cover 110 of FIG. 3, and the resulting frame 10 of FIG. 2, comprise comers with outer sidewalls that all have a radius of curvature of approximately 2 cm.

[0057] In the depicted embodiment, reusable frame 10 is a two-piece frame formed by mating, and detachably attaching, an upper cover 110 to a lower base 210. In some embodiments, upper cover 110 may comprise one or more latches 171 that are configured to be secured to complementary latches 271 of lower base 210. In some embodiments, a latch 171 of upper cover 110 may comprise one or more latch members 172 that are integral with upper cover 110 (rather than being e.g. attached to upper cover 110 by hinges); two such integral latches 171 and their respective integral latch members 172 are visible in FIG. 11. Such latches 171 and their latch members 172 may be outwardly deflectable so that as upper cover 110 is mated to lower base 210, each latch member of each latch 171 can pass outward of a latch catch 272 of complementary latch 271 of lower base 210. (Complementary latch 271 and its latch catch 272 will often be integral with lower base 210; one such complementary latch 271 and its latch catch 272 are visible in FIG. 12.) When upper cover 110 is fully mated to lower base 210, each latch 171 and its latch member 172 can return to its undeflected condition to hold lower base 210 and upper cover 110 together. At such time as it is desired to separate the frame pieces, latch 171 can be temporarily deflected outward to disengage latch 171 from complementary latch 271. The previously -mentioned choice of material of which at least upper cover 110 is made, as well as the thickness of an upper cover sidewall that comprises a latch 171, can facilitate the ability to outwardly deflect the latch-bearing-sidewall of the upper cover to the extent that the latch 171 can be latched, and unlatched, as desired.

[0058] In some embodiments, upper cover 110 may comprise one or more detent features 173 that are configured to interact with one or more complementary detent features 273 of lower base 210 to enhance the security with which lower base 210 and upper cover 110 are held together. In the depicted design, detent feature 173 (visible in FIG. 11) of upper cover 110 is an inward-protruding ridge and complementary detent feature 273 (visible in FIG. 12) of lower base 210 is an outwardly -protruding ridge. Lower base 210 also comprises an additional complementary detent feature 274 (visible in FIG. 12) in the form of an inward recess immediately below ridge 273. Detent feature 173 of upper cover 110 can rest below complementary detent 273, and can be received into recess 274, to enhance the functioning of the detent arrangement.

[0059] Other arrangements may be used to further enhance the securing of upper cover 110 to lower base 210. For example, lower base 210 may comprise one or more bollards 275 (visible in FIG. 12) that are configured so that when upper cover 110 is mated to lower base 210, bollards 275 of lower base 210 will impinge on a particular wall-section 175 (denoted in FIG. 11) of upper cover 110. This will urge wallsection 175, and the portion of upper cover 110 to which wall-section 175 belongs, generally inward. This can hold a portion of upper cover 110 and a portion of lower base 210 together more firmly, which can enhance the functioning of the above-described detent arrangement. To separate upper cover 110 from lower base 210, the above-mentioned latches 171 of upper cover 110 can be temporarily manually deflected slightly outward them from the catches 272 of complementary latches 271 of lower base 210. If needed, the portion of lower base 210 that comprises bollards 275 may be temporarily deflected slightly outward, so that the detent features 173 of upper cover 110 may be more easily separated from the complementary detent features 273 and 274 of lower base 210.

[0060] In some embodiments, frame 10 may be provided with one or more handles. Typically, at least one handle will be provided on each of the four frame portions, since any of the frame portions may end up being the one that is exposed through an access slot of the HVAC system and that will be grasped in order to remove the framed air filter from the HVAC system. In the exemplary arrangement of FIG. 11, handles 161 are provided in all four portions of upper cover 110. In the depicted embodiment, each primary portion

[0061] 112 has one such handle 161, centrally located along the primary portion, while each secondary portion

[0062] 113 has two such handles 161, spaced along the secondary portion. (In some embodiments, handles may be provided in lower base 210 in addition to, or instead of, being provided in upper cover 110.) In the depicted embodiment of FIG. 11, each handle 161 is generally T-shaped, comprising a shank 163 that supports a graspable flange 164. Each shank 163, flange 164, and handle 161 is an integral part of upper cover 110. Also, each handle 161 is located within an inward recess 162 provided in an outer sidewall of the respective portion of upper cover 110. This inward recessing of the handles can provide that the handles do not protrude beyond the outer sidewalls of frame 10 in a way that would compromise the ability of the framed air filter to be installed in a filter-receptacle of an HVAC system.

[0063] Downstream sealing apron

[0064] In some embodiments frame 10 (in particular, the lower base 210 of frame 10) may be configured to minimize air leaks around the outside of frame 10 when the framed air filter 1 is installed into a filterreceptacle of a powered air-handling apparatus in a “standard” configuration. For example, in some embodiments lower base 210 may comprise a downward sealing apron 284 (as pointed out in FIG. 4) provided by a downstream (as-installed) surface of a sealing “lip” 250 that extends at least generally around the entire perimeter of lower base 210. This downstream surface of sealing lip 250 may be at least substantially planar, so that when framed air filter 1 is inserted into a filter-receptacle of a powered airhandling apparatus (in a standard configuration as discussed elsewhere herein), this downstream surface of sealing lip 250 will be in contact with a surface of a flange, fixture, etc. of the filter-receptacle of the airhandling apparatus. (In fact, the downstream surface of sealing lip 250 will tend to be held against the surfaces of the filter-receptacle of the air-handling apparatus, by the pressure developed by the air impinging on the upstream face of the framed filter.) The thus-formed sealing apron 284 may thus establish a reasonably air-tight seal against the filter-receptacle of the air-handling apparatus. Sealing apron 284 can thus establish a “dead-end” path so that any (potential) air leakage that does occur e.g. around the outward edges of frame 10, will have nowhere to go. Such arrangements can enhance the filtration performance of framed air filter 1 as installed in a powered air-handling apparatus.

[0065] It is noted in passing that the terminology that sealing lip 250 extends at least “generally” around the entire perimeter of lower base 210 is used in view of the fact that sealing lip 250 is interrupted at the location of the two above-described latches 271, as is evident from inspection of FIG. 4. However, in these locations, portions of the outer sidewall 123 of upper cover 110 fill in for portions of the “missing” section of lip 250 of lowerbase 210. Also, in these locations, various surfaces of lower base 210 are closely abutted, e.g. contacted, by various surfaces of upper cover 110. This being the case, the absence of a sealing lip 250 in these locations has not been found to not significantly adversely affect the filtration performance of framed air filter 1 as installed in a powered air-handling apparatus.

[0066] In general, upper cover 110 and lower base 210 can be brought together to form frame 10, without the need to include any gasketing, caulking, adhesive, weatherstripping, sealant, or the like. In particular, in the assembled frame 10, various surfaces of upper cover 110 and lower base 210 are brought together as simple butt junctions, without any gasketing material or the like. For example, in the exemplary arrangement shown in FIG. 5, a lowermost terminus 181 of outer sidewall 122 of primary portion 112 of upper cover 110 is abutted against an upward-facing surface of a lower lip 250 of a lower flange 226 of primary portion 212 of lower base 210 to form a butt junction. Similarly, in the exemplary arrangement shown in FIG. 6, a lowermost terminus 181s of outer sidewall 123 of secondary portion 113 of upper cover 110 is abutted against an upward-facing surface of a lower lip 250s of lower flange 227 of secondary portion 213 of lower base 210 to form a butt junction. Various other surfaces of upper cover 110 and lower base 210 are similarly brought together; such arrangements have been found to provide excellent filtration performance without the need for any gasketing materials or the like.

[0067] In many embodiments, frame 10 may be a two-piece design in which lower base 210 and upper cover 110 are completely separable from each other as evident in FIGS. 2 and 3. In other embodiments, frame 10 may comprise a clamshell design in which lower base 210 and upper cover 110 are hingedly attached to each other. As noted, frame 10 (and its lower base 210 and upper cover 110) is reusable, by which is meant that frame 10 can be used with a succession of air filters 400 such that frame 10 has a usable service life that is far greater (e.g. at least ten times greater) than the typical usable service life of the air filters 400 that are installed in frame 10. At the end of its service life, frame 10 may be e.g. recycled, composted, discarded, etc.

[0068] As noted, in many embodiments, lower base 210 and upper cover 110 may be made by injection molding of any suitable organic polymeric thermoplastic material, e.g. acrylonitrile-butadiene-styrene (ABS), polyamide, polyoxymethylene, polypropylene, and so on. Any of the various portions and components of lower base 210 and upper cover 110 may be of any suitable thickness. As previously noted, some particular components may have a thickness that is specifically chosen to impart the desired balance of strength and deflectability. Such components may include e.g. a sloped section of a flange, that is desired to be able to deflect at least somewhat when it impinges on an edge of an access slot of an HVAC system, and a sidewall that is desired to be able to deflect so as to allow the above-described latching and unlatching. In some embodiments, the upper struts 193 / 194 and / or the lower struts 293 / 294 of the upper cover and the lower base, may be configured to provide at least some deflectability, for reasons discussed elsewhere herein. Other components, e.g. various components of lower base 210, may not be likely to encounter any need to deflect, thus such components can have any desired thickness.

[0069] As evident in various Figures herein, in some embodiments lower base 210 may comprise multiple sidewalls or sidewall sections, and may comprise various cavities, trenches, and the like. Such features and arrangements can be for any desired purpose (e.g., to provide the framed air filter with requisite overall mechanical robustness, while minimizing the total weight of the framed air filter), and can be arranged in any suitable manner. Similarly, as evident in various Figures herein, at least some portions of the outer sidewall of upper cover 110 may have one or more inward scallops (one such exemplary inward scallop is identified by reference number 118 in FIG. 3). Such an arrangement may enhance the overall mechanical robustness of the framed air filter. (Identification of previously -discussed features such as outermost planar surface 128 of outer sidewall 122 of upper cover 110, and the calculation of outward taper ratios and associated parameters, can be done on areas of upper cover 110 that do not comprise an inward scallop.)

[0070] Pleated air filter and installation in frame

[0071] As disclosed herein, an air filter 400 can be installed into the above-described reusable frame 10. In some embodiments, such an air filter 400 will be pleated; an exemplary pleated air filter 400 is shown, from the upward side, in FIG.7. By “pleated” is meant a sheet-like entity that has been folded into rows of generally parallel, oppositely oriented folds that provide alternating peaks and valleys on both sides of the entity. As shown in FIGS. 8-9, pleated air filter 400 includes a plurality of pleat-panels 401 (integrally connected to each other at pleat-tips) and comprises an upward side 405 with upward pleat tips 413, and a downward side 406 with downward pleat tips. Such a pleated air filter will exhibit a pleat direction (Dp, indicated in FIGS. 1 and 8) that is parallel to the long axes of the pleat tips, as previously noted.

[0072] A pleated air filter 400, as configured to be installed in a reusable frame, is often referred to as a

[0073] “pleatpack”. In some embodiments, a pleatpack 400 can be provided to an end-user in a compacted configuration (equivalently, a collapsed condition), in which the pleat tips (and pleat-panels) are crowded quite close together or even in contact with each other. Such a compacted pleated air filter can be expanded (e.g. by an end-user) into its in-use configuration (depicted in FIG. 7) for installation into reusable frame 10. Pleated air filter 400 will thus have an expansion direction DE(indicated in FIGS. 1, 7 and 8) that is perpendicular to the pleat direction DPand along which the pleated air filter can be expanded from a compacted configuration to an expanded, in-use configuration. When pleated air filter 400 is installed into frame 10, the expansion direction DEof pleated air filter 400 will be parallel to the above-described secondary direction S of frame 10, and the pleat direction DPof pleated air filter 400 will be parallel to the above-described primary direction P of frame 10.

[0074] In many embodiments, pleated air filter 400 may be provided (e.g. in a kit) in a compacted configuration, and expanded into the in-use configuration (e.g., a condition in which the pleated air filter has a length that matches the length of the filter-receiving cavity 30 of frame 10) by an end-user. The pleated air filter is configured to quickly and easily transition from a collapsed configuration to an expanded, in- use configuration. In some embodiments, a removable wrapper or other packaging can be provided to initially retain the air filter in the collapsed state, and can be removed to allow expansion. The air filter does not require a conventional, factory -installed rigid frame permanently surrounding the pleated air filter, and can advantageously be packaged, stored, shipped, inventoried, and so on, in the collapsed state.

[0075] A pleated air filter 400 can thus be expanded at least once from a collapsed condition to an expanded, in-use condition, along an expansion direction DE; in many embodiments, the pleated air filter can only expand along this single direction. In some embodiments, the pleated air fdter can be repeatedly transitioned back and forth between an expanded, in-use condition and a collapsed condition. However, in some embodiments the air filter may only need to be expandable from a collapsed condition to an expanded, in-use condition a single time. That is, in some such embodiments, the pleated air filter may not need to be collapsible back to the original collapsed condition.

[0076] With reference to FIG. 7, pleated air filter 400 will comprise first and second opposing ends 402Pand 402s, which are termed “primary” ends as noted earlier. Primary ends 402Pand 402s will respectively comprise securing tabs 501Eand 501s that are each configured to be inserted into an upward-open-ended elongate slot 260 of a primary portion 212 of lower base 210 in order to secure pleated air filter 400 to lower base 210. (Such an arrangement is shown, in exploded view, in FIG. 9.) In some embodiments, such a securing tab 501 will be provided by an end pleat-panel 407 that is reinforced to exhibit increased stiffness, mechanical robustness, etc. (so that it can serve as a securing tab) as discussed in detail later herein. First and second reinforced end pleat-panels 407 of pleated air filter 400 are configured to be inserted into upward-open-ended elongate slots 260 of the first and second primary frame portions 12 of reusable frame 10.

[0077] In some embodiments, only securing tab 501 and end pleat-panel 407 are inserted into slot 260, as in the exemplary arrangement shown in FIG. 9. In such embodiments, penultimate pleat-panel 410 will reside inward of primary inward sidewall 264 and end upper pleat tip 408 will generally overlie the upper end of inward sidewall 264. In some embodiments, one or more additional pleat-panels may be gathered with end pleat-panel 407 and securing tab 501, to be collectively inserted into slot 260. For example, in some embodiments, penultimate pleat-panel 410 and its inward nearest-neighbor pleat-panel (unnumbered in these Figures) may be gathered with end pleat-panel 407 and inserted into slot 260. In such an arrangement, penultimate upper pleat tip 409 will generally overlie the upper end of inward sidewall 264.

[0078] For the above purposes, upward-open-ended elongate slots 260 can be provided in lower base 210 as visible in FIGS. 3 and 5. Securing tabs 501 (e.g., in the form of reinforced end pleat-panels 407) can be inserted into slots 260 to secure the primary ends 402 of pleated air filter 400 to lower base 210, as indicated in FIG. 9 and as visible in FIG. 10. With this accomplished, upper cover 110 can then be mated to lower base 210 and attached thereto, to form the completed, ready -for-use framed air filter 1. Further aspects of providing a frame with elongated slots and providing a pleated air filter with securing tabs to facilitate securing the pleated air filter in the frame, are discussed in detail in U.S. Provisional Patent Application 63 / 452484 and in the resulting PCT Patent Application PCT / IB2023 / 061115; in U.S. Provisional Patent Applications 63 / 607822 and 63 / 684639 and in U.S. Patent Application 18 / 952714 resulting therefrom; and, in U.S. Provisional Patent Applications 63 / 607966 and 63 / 684727 and in U.S. Patent Application 18 / 952514 resulting therefrom, all of which are incorporated by reference herein in their entirety. (These documents also provide further details of pleated filters that are expandable and compactable.)

[0079] The above-described general arrangements can be particularly configured to ensure that the desired advantages disclosed herein can be achieved, as illustrated in FIG. 9. FIG. 9 is a cross-sectional side view similar to FIG. 5, except taken at a slightly different location along a primary frame portion 12. FIG. 9 also includes pleated air filter 400 (FIG. 9 is thus a cross-sectional view of a primary portion of the framed air filter 1 of FIG. 1.) In FIG. 9, upper cover 110, pleated air filter 400, and lower base 210, are all exploded (along the upward-downward direction) away from each other so that each item can be more clearly seen.

[0080] As shown in FIG. 9, an upward-open-ended elongate slot 260 of a primary portion 212 of lower base 210, and a moderately -sloped inward sloped section 133 of a primary portion 112 of upper cover 110, can be configured so that when a securing tab 501 of a primary end 402 of pleated air fdter 400 is seated in slot 260, the moderately-sloped inward sloped section 133 of primary portion 112 of upper cover 110 will not contact any upper pleat tip 413 of pleated air filter 400. (Inspection of FIG. 5 reveals that the same result will be achieved when seating a securing tab in the particular part of elongate slot 260 depicted in FIG. 5.) In other words, these items can be configured and arranged so that the tapered section of upper cover 110 (in particular, the underside of section 133), does not extend so far inward as to overlie (in particular, to contact or crush) end upper pleat tip 408, or penultimate upper pleat tip 409, or any other upper pleat tip, of the pleated media. (It is noted in passing that because of the particular cross-sectional cut location used in FIG. 9, the underside of section 133 is not visible; however, it is shown in dotted lines to denote its location.) That is, a tapered frame can be used for the purposes discussed herein, without the frame-tapering resulting in any crushing (or any other adverse affect) of the pleated air filter. A pleated air filter 400 will comprise first and second opposing edges 403Fand 403 s, which will be termed “secondary” opposing edges. By definition, these secondary edges of pleated air filter 400 are “corrugated” edges; the above-described primary opposing ends 402 of air filter 400 (that bear securing tabs 501) are not corrugated. (A “corrugated” edge of a pleated air filter is one that exhibits an overall, generally zig-zag shape when viewed along the pleat direction Dp, as is evident from FIGS. 8 and 9; the term corrugated does not imply that the edges of individual pleat-panels are nonlinear.) In a framed air filter 1 as disclosed herein, the first and second secondary, corrugated opposing edges 403Fand 403 s of pleated air filter 400 will be closely abutted against (i.e., in contact with) inward surfaces 269 of inward sidewalls 268 of secondary frame portions 13 of frame 10, as evident from FIG. 10. In the depicted embodiment, these inward secondary sidewalls 268 are provided by lower base 210.

[0081] In some embodiments, pleated air filter 400 may be configured so that when pleated air filter 400 is installed in frame 10 so that corrugated edges 403 of pleated air filter 400 are abutted against the inward surfaces 269 of inward secondary sidewalls 268 of frame 10, the corrugated edges 403 of air filter 400 may be able to locally conform to surfaces 269. That is, air filter 400 may comprise filter media that is at least somewhat compliant so that corrugated edges 403 of air filter 400 are, on a local scale, flexible and resiliently conformable so that they can locally bend, conform, and so on, when abutted against surface 269 of frame 10. (In such embodiments, a stiffening layer as described later herein may be completely absent; or, the stiffening layer may terminate inward of the corrugated edges of the filter media.) This can provide that the corrugated edges 403 of pleated air filter 400 are able to “self-seal” against the inward surfaces 269 of inward secondary sidewalls 268 of frame 10. This can minimize any air leaks around corrugated edges 403 of pleated air filter 400, without any need for the corrugated edges of pleated air filter 400 to be adhesively bonded to the inward secondary sidewalls 268 of frame 10 (in general, without the need for any portion of pleated air filter 400 to be adhesively bonded to frame 10); and, without the need for any added item or material to serve as a gasket, seal, caulk, space-filler, etc. Thus in some embodiments, neither pleated air filter 400 nor frame 10 will comprise any added item (such as e.g. a strip of resilient foam or the like) that serves to provide a gasketing, sealing, and / or space-filling function.

[0082] Inspection of FIG. 10 reveals that with arrangements of the general type described above, a corrugated / secondary edge 403 of pleated air filter 400 can be abutted against an inward surface 269 of an inward secondary sidewall 268 of lower base 210. As evident from FIG. 6, such an arrangement can provide that when upper cover 110 is mated and attached to lower base 210 (with pleated air filter 400 in place) to form framed air fdter 1, the corrugated edge 403 of air filter 400 will be inwardly positioned relative to moderately-sloped inward sloped section 133s of secondary portion 113 of upper cover 110. This can provide that in the framed air filter, this moderately-sloped inward section 133s of upper cover 110 does not impinge on the corrugated edge 403 of pleated air filter 400. Inspection of FIGS. 6 and 10 reveals that in some embodiments, a substantially -unsloped inwardmost section 135S of secondary portion 113 of upper cover 110, can overlie not just corrugated edge 403, but also a corrugated edge area that is e.g. within 0.5- 3.0 cm of corrugated edge 403.

[0083] A pleated air filter 400 will exhibit a pleat spacing Ps and a pleat height PH, as respectively indicated in FIGS. 8 and 9. These are well-known parameters for characterizing a pleated structure, the pleat spacing being the distance between successive same-side pleat tips and the pleat height being the distance, along the Upward-Downward direction, between nearest-neighbor opposite-side pleat tips. The pleat spacing may change greatly depending on the degree to which the pleated air filter is compacted or expanded; the pleat height may change slightly depending on the degree of compaction or expansion.

[0084] Air filter compression

[0085] In some embodiments, a reusable frame 10 and a pleated air filter 400 may be configured so that the pleated air filter 400 can be held in the filter-receiving cavity 30 of frame 10 in slight compression (along the upward-downward direction). This can enhance the ability frame 10 to retain pleated air filter 400 securely in an optimum geometric configuration (e.g. without any of the pleats becoming bunched, accordioned, etc.), in spite of the air pressure exerted by impinging air in an HVAC system. Such arrangements may be achieved by setting the “depth” of at least a portion of the filter-receiving cavity 30 of frame 10 to be slightly less than the pleat height of pleated air filter 400. The pleat height is the distance, along the upward-downward direction, between nearest-neighbor opposite-side pleats, as illustrated by arrow Ph in FIG. 9. The “depth” of cavity 30 of frame 10 is the distance, along the upward-downward direction, from the “floor” of cavity 30 (such a floor will typically be defined by an upward-facing surface of a component of lower base 210) to the “ceiling” of cavity 30 (such a ceiling will typically be defined by a downward-facing surface of a component of upper cover 110). An exemplary cavity depth (in the depicted case, between a ceiling defined by a downward-facing surface of a substantially -unsloped section 135s of upper flange 24, and a floor defined by an upward-facing surface of a substantially-unsloped section 235 of lower flange 26) is denoted as Dcin FIG. 6.

[0086] In some embodiments, an arrangement in which a pleated air filter 400 is held in slight compression can be characterized by way of the cavity depth Dcin the previously -described central area (e.g. as denoted by dashed box 218 in FIG. 3) of window 217 of the frame. In central area 218, the cavity depth Dcwill be defined by the distance (again, along the upward-downward direction) between the downward faces of upper struts 193 and 194 of upper cover 110, and the upward faces of lower struts 293 and 294 of lower base 210. Setting the cavity depth in central area 218 of frame 10 at a desired value relative to the pleat height PH can provide that in the assembled frame, the pleated air filter is held in slight compression; not enough to significantly deform the individual pleats or the pleated air filter as a whole, but enough to ensure that pleated air filter 400 is securely held in an optimum position and condition for performing filtration. In various embodiments, the cavity depth of central area 218 of frame 10 may range from e.g. 100, 99, 98, or 97 %, to 94, 95, or 96 %, of the in-use pleat height PH of pleated air filter 400. By way of a specific example, the exemplary frame 10 as disclosed herein is configured to exhibit a cavity depth Dcof approximately 0.72 inches and the exemplary pleated air filter 400 as disclosed herein is configured to have a pleat height PH of 0.75 inches, thus the cavity depth will be approximately 96 % of the pleat height. Any such cavity depth will be measured in the absence of a pleated air filter 400 and with the upper and lower struts in a resting, undeflected condition. In some embodiments, at least the upper stmts may be at least slightly deflectable to aid in achieving the appropriate compression of the pleated air filter. In some embodiments, at least the upper struts may have a gradual inward taper, i.e. they may be slightly thinner (in the upward-downward direction) within central area 218, and slightly thicker in locations closer to the sides of the frame.

[0087] In some embodiments, the sidewalls of the filter-receiving cavity 30 may be at least generally, substantially or essentially completely provided by primary inward sidewalls 264 (as visible in FIG. 5) and secondary inward sidewalls 268 (as visible in FIG. 6) of lower base 210, as evident from inspection of FIG. 12. In such embodiments, a major proportion (e.g., at least 80, 90, or 95 %) of pleated air filter 400, or at least generally the entirety of pleated air filter 400, may reside within a subcavity defined by inward sidewalls 264 and 268 of lower base 210, as in the exemplary arrangement depicted in FIG. 10. In some such cases, the upper pleat tips 413 of pleated air filter 400 may be the only parts of pleated air filter 400 that extend upwardly beyond this subcavity, as is evident from inspection of FIG. 10. Such a design can ensure that upper cover 110 can be easily fitted onto lower base 210 without undesirably impinging on (e.g., pinching) the corrugated edges 403 of pleated air filter 400. (Such designs can however still allow the above-described slight compression of pleated air filter 400, if desired.) In some such embodiments, in the framed air filter 1, the only part(s) of upper cover 110 that may come into contact with the upper pleat tips 413 of the pleated air filter 400, will be the previously-described upper struts 193 / 194 and / or the inwardmost sections 135 of upper cover 110.

[0088] In some embodiments, lower base 210 may comprise first and second support shelves 228 at first and second opposing secondary ends of lower base 210 (one such shelf 228 is visible in FIGS. 3 and 12). Such a support shelf may underlie a corrugated edge 403 (and a corrugated edge area 404) of pleated air filter 400. When framed air fdter 1 is installed in a powered air-handling apparatus in a standard configuration, support shelves 228 will be positioned downstream of pleated air filter 400 and may support the corrugated edges / areas of pleated air filter 400 against the force developed by the impinging airstream. (The previously -described downward struts 293 / 294 of lower base 210 may also support the pleated air filter against the force of the impinging airstream, as noted earlier.) The inwardmost tips of support shelves 228 will define the secondary sides of the above-mentioned window 217 of lower base 210. In the depicted embodiment, no such support shelves are present at the opposing primary ends of lower base 210. Rather, the primary sides of window 217 are defined by the inward surfaces of primary inward sidewalls 264, as evident in FIGS. 3 and 12.

[0089] Pleated air filter 400 comprises a layer of filter media of any suitable type and composition. Such media (and the resulting air filter) is typically sheet-like, with a length along the expansion direction DE, and a width along the pleat direction Dp, that are considerably greater than the local thickness of the air filter and its filter media. Herein, the term “width” is used for the dimension of pleated air filter 400 along the pleat direction and for the dimension of frame 10 along its primary direction; the term “length” is used for the dimension of pleated air filter 400 along its expansion direction and for the dimension of frame 10 along its secondary direction. These terms are used purely for convenience of description. The length of pleated air filter 400 and / or frame 10 need not necessarily be greater than its width; in fact, in the exemplary designs shown e.g. in Figures herein, the “width” of these items is indeed greater than their “length”.

[0090] In some embodiments, filter media may be, or include, a nonwoven material such as e.g. a meltspun / spunbonded nonwoven web or a meltblown nonwoven web. In some embodiments, filter media may comprise fiberglass fibers. In some embodiments, the filter media may be configured to perform air filtration so as to remove particulates from a stream of moving air. Nonwoven webs which may be used as, or as a layer, of, air filter media can be a high loft spunbond web, such as described, for example, in U.S. Patent 8162153. In some embodiments, the filter media can be, or include, a low loft spunbond web, such as those described in U.S. Patent 7947142. In some embodiments, an electrostatic charge is optionally imparted into or on to material(s) of the filter media. Thus, the filter media can be an electret nonwoven web. Electric charge can be imparted to the filter media in a variety of ways as is well known in the art, for example by hydrocharging, corona charging, etc. (e.g. as described in U.S. Patent 7947142). In other embodiments, the filter media is not electrostatically charged. Pleats can be formed in the filter media using various methods and components as are well known in the art, for example those described in U.S. Patents 6740137 and 7622063. In some embodiments, the filter media may be a diamond-pleated media of the general type as described e.g. in U.S. Provisional Patent Application 63 / 530463, entitled DIAMOND- PLEATED FILTER MEDIA, and as described in the resulting U.S. Patent Application 18 / 780963, both of which are incorporated by reference in their entirety herein.

[0091] In some embodiments, pleated air filter 400 may optionally comprise a stiffening layer. Such a stiffening layer is, by definition, a layer of material that is permanently attached (e.g. laminated) to the above-described layer of filter media. Such a stiffening layer may be desirable in some cases to increase the overall stiffness and pleatability of the air filter. By definition, a stiffening layer is co-pleated with the filter media, meaning that the stiffening layer is attached to the layer of filter media, after which both layers are pleated in the same pleating operation to form pleated air filter 400. If present, a stiffening layer may be e.g. in the form of a layer of mesh, netting, or the like, that is collectively provided by filaments that define through-openings, and that exhibits a very high (e.g., greater than 90, 95, or 98 %) open area so as to be highly air-transmissive. In some embodiments, such a mesh may be comprised of metal filaments and may be e.g. adhesively bonded to the surface of the filter media. Such bonding may be achieved e.g. by lamination of the wire mesh to the filter media while both items are not yet pleated (and are e.g. in a roll or jumbo format), with the bonded layers then being co-pleated thereafter. However, in some embodiments pleated air filter 400 will not comprise any stiffening layer of any kind. In some embodiments, pleated air filter 400 may include one or more elongate members 442 that are configured to limit the expansion of each of the pleats of the pleated air filter to a predetermined length so that the pleated air filter exhibits a desired in-use configuration with a predetermined pleat spacing. Any number of such pleat-spacing-limiting elongate members, e.g. one, two, three, or more, may be present. Such members may be on the upward or downward side of the pleated air filter, or on both. They may extend at least generally along the expansion direction of the pleated air filter and may be spaced apart along the pleat direction of the pleated air filter, and may be bonded to upward or downward pleat tips of the pleated air filter.

[0092] In the exemplary illustrations of FIG. 1, 7 and 10, members 442 are in the form of elongate ribbons that are bonded to upper pleat tips 413 of the pleated air filter. Even if in the form of relatively wide ribbons of the general type depicted in these Figures, such members typically will not have a major affect on airflow or filtration performance. However, if desired, such a ribbon may be chosen to be air-transmissive, e.g. in the form of a nonwoven scrim or netting. Thus in various embodiments, any such member or members may take the form of a nonwoven scrim, a netting, a wire mesh, a set of filaments, and so on. Such members, individually and collectively, will be distinguished from an above-described stiffening layer, by virtue of the pleat-spacing-limiting members 442 being bonded only to the pleat tips of the pleated air filter rather than being co-pleated with the pleated air filter. In some embodiments, such members may take the form of a set of extruded filaments of the general type described in U.S. Patent Application Publications 2021 / 0229022 and 2021 / 0229023, both of which are incorporated by reference in their entirety herein.

[0093] In some embodiments, any such members will be flexible (e.g. so that the members can fold or gather to accommodate their excess length when the pleated air filter is collapsed); in some such embodiments, any such entities may be inelastic so as to limit the pleat expansion to a desired amount that establishes a desired in-use pleat spacing. For example, such a member may take the form of one or more ribbons, strips, filaments, etc. that is attached to the pleat tips and that, when extended to its maximal length, provides a “dead-stop” at a desired span. Thus in some embodiments such an entity may be inelastic, meaning that it exhibits an elongation at break of less than 5 %. In other embodiments, any such entity may be elastic, e.g. so as to exhibit an elongation at break of at least 5, 20, 50, 100, or 200 %. Any such members may be bonded to the pleat tips of the pleated air filter in any suitable way. For example, a pressure-sensitive adhesive may be disposed on the surface of the members at least at locations where the members will contact the pleat tips. Or, the members may be ultrasonically bonded to the pleat tips, or may be melt- bonded thereto (e.g. by being extruded and extrusion-bonded to the pleat tips). In some embodiments, the members may be bonded to the pleat tips by way of hot melt adhesive.

[0094] As noted, pleated air filter 400 will comprise first and second securing tabs 501 at the first and second opposing primary ends 402 of filter 400. First and second securing tabs 501 are respectively insertable into first and second upward-open-ended elongate slots 260 of lower base 210 to secure pleated air filter 400 to lower base 210. As mentioned, in some embodiments securing tabs 501 may be provided by end pleat-panels 407 of pleated air filter 400, at first and second opposing primary ends 402 of pleated air filter 400. Any such end pleat-panel 407 that serves as a securing tab 501 may be a reinforced pleatpanel, by which is meant that the end pleat-panel, while comprising the same filter media as the other pleatpanels, has one or more entities mounted thereon, and / or is subjected to a suitable treatment, to significantly increase the stiffness of the end pleat-panel in comparison to the other pleat-panels of the pleated air filter. A reinforced end pleat-panel can thus be configured to have appropriate physical properties to be seated into an elongate slot 260 of frame 10 and to be securely held therein.

[0095] In some embodiments, a reinforced end pleat-panel 407 that can serve as a securing tab 501 may be obtained by taking a separately -made item such as a sheet-like reinforcing material 502 (e.g. a piece of suitably sized and shaped chipboard of appropriate thickness) and mounting it on an inward face 411 and / or an outward face 412 of end pleat-panel 407. As depicted in the exemplary arrangement of FIGS. 8 and 9, such a reinforcing sheet 502 may comprise an outward segment 503 that is attached to outward face 412 of end pleat-panel 407 and an inward segment 504 that is attached to the inward face 411 of the end pleatpanel. In some convenient embodiments, the inward and outward segments 504 and 503 can be segments of a single piece 502 of chipboard that is “wrapped around” the downward tip 414 of end pleat-panel 407 such that a downward apex 505 of the chipboard is located downward of the downward tip 414 of the end pleat-panel (the inward and outward segments 504 and 503 of reinforcing sheet 502 will thus integrally meet at apex 505).

[0096] Any such reinforcing sheet 502 may be bonded to the inward and / or outward face of an end pleatpanel in any suitable way, e.g. by adhesive bonding such as by the use of hot melt adhesive, by the use of mechanical fasters such as e.g. staples, and so on. In some embodiments, various other methods to reinforce an end pleat-panel may be used, whether alone or in addition to the arrangements described above. For example, an end pleat-panel of the air filter may be impregnated with a liquid resin that, after hardening, will render the end pleat-panel stiff and rigid. Another possibility is to gather several panels at the end of the pleated air filter, press them together, and attach them to each other (in any suitable way) to collectively form, in effect, a single, thickened and stiffened end pleat-panel that can serve as a securing tab. In another variation, a reinforcing sheet 502 can be attached to (e.g. wrapped around) several such gathered pleatpanels rather than being attached to (e.g. wrapped around) a single end pleat-panel 407. (Such an arrangement will be termed herein as the inward segment 504 of sheet 502, being indirectly attached to the inward face 411 of end pleat-panel 407.)

[0097] However made, a securing tab 501 (e.g. as provided by a reinforced end pleat-panel 407) will typically be elongate with a long axis that is aligned with the pleat direction Dpof the air filter, as is evident e.g. from FIG. 8. Such a securing tab 501 will have a downward, leading end (e.g. as provided by the abovedescribed downward apex 505 of securing tab 501) that can be inserted into an upward-open-ended elongate slot 260 of frame 10, and will have an upward, trailing end that is proximate and end upper pleat tip 408 of end pleat-panel 407 at which end pleat-panel 407 integrally meets penultimate pleat-panel 410, as evident from FIGS. 8 and 9. When securing tab 501 is fully seated in slot 260, downward apex 505 of securing tab 501 may rest on or near the downward end 261 of slot 260, as evident from FIG. 9. (Also, when securing tab 501 is fully seated in slot 260, inward primary sidewall 264 will typically be positioned in the space between end pleat-panel 407 and penultimate pleat-panel 410, e.g. with end upper pleat tip 408 being positioned generally atop the upper terminus of inward sidewall 264.)

[0098] Foldable Handle

[0099] In some embodiments, a reinforcing sheet 502 that provides a securing tab 501, will comprise a handle segment 506, visible in perspective view in FIG. 7 and in side view in FIGS. 8 and 9. In some embodiments, handle segment 506 may be integrally, hingedly connected to outward segment 503 at an integral, hinged connection 507. Handle segment 506 will not be attached to end pleat-panel 407 but rather can protrude above 407 and can be rotated about hinged, integral connection 507. Handle 506 thus can be used to manually grasp and manipulate pleated air filter 400. Once the securing tabs 501 of pleated air filter 400 are seated in elongate slots 260 of lower base 210, handle 506 can be folded generally inward so that handle 506 is oriented at least generally parallel to the plane of the primary and secondary axes of lower base 210. This will be referred to as handle 506 being in a “flat-folded” condition and is depicted in FIGS. 7-10. This done, upper cover 110 can then be mated to lower base 210 and attached thereto. This will result in a configuration as shown in FIG. 1, in which a portion of the flat-folded handle 506 is positioned between an upward side 405 of pleated air filter 400, and a substantially -unsloped inwardmost section 135 of upper cover 110. Such a configuration is also shown (in exploded format) in the side view of FIG. 9. As evident from FIG. 9, in some embodiments this will result in the flat-folded handle segment 506 upwardly overlying the previously-described end upper pleat tip 408. In some such embodiments, the flat-folded handle segment 506 may also overlie a penultimate upper pleat tip 409. It will be appreciated that such arrangements allow handle segment 506 to be positioned so that it does not interfere with the ability to mate and attach the upper cover 110 to the lower base 210. In many embodiments, handle segment 506 may extend only along a limited portion of the “width” of pleated air filter 400 in the secondary direction. Such an arrangement can ensure that handle segment 506, when flat-folded as described above, does not have any significant impact on the filtration performance of pleated air filter 400, since incoming air can easily bypass around the edges of handle segment 506 to reach the pleat-panels that handle-segment 506 overlies.

[0100] Returning to frame 10, reusable frame 10 may comprise a lower base 210 and a upper cover 110 that can be mated and attached to form frame 10 as described earlier herein. Lower base 210 and upper cover 110 are shown detached from each other (in the absence of pleated air filter 400) from the upward side in FIG. 2 and from the downward side in FIG. 3. Lower base 210 will comprise first and second opposing primary portions 212 and first and second secondary portions 213. Upper cover 110 will similarly comprise first and second opposing primary portions 112 and first and second secondary portions 113. When lower base 210 and upper cover 110 are brought together (as depicted in FIG. 2, with pleated air filter 400 omitted), the first and second primary portions of the lower base and the upper cover will collectively provide the first and second primary portions 12Fand 12s of frame 10, and the first and second secondary portions of the lower base and the upper cover will collectively provide the first and second secondary portions 13Fand 13s of frame 10.

[0101] In the depicted embodiment, the first and second opposing primary portions 212 of lower base 210 respectively comprise first and second upward-open-ended elongate slots 260. An exemplary such slot 260 is shown in side view in FIG. 5. Each such upward-open-ended elongate slot 260 will have a long axis that is aligned with the frame’s primary axis / direction (again, denoted by axis “P” in various Figures) of the frame. Each slot 260 will have an upward end that is open and a downward end 261 that is at least partially (e.g. fully) closed, e.g. by way of being provided with a slot floor as evident in FIG. 5. In some embodiments, the upward, open end of the slot will comprise an arcuate entry 262 to make it easier to guide an above-described securing tab 501 of pleated air filter 400 into slot 260. Each slot 260 will have a slot depth that extends in a generally downward direction from its open upward end to the slot floor at the downward end 261 of the slot. The slot depth can be configured so that the slot is able to accept a securing tab of a particular size.

[0102] As noted, two such slots 260 are present, at opposing primary ends of lower base 210, so that the first and second securing tabs 501 of the air filter can be respectively securely seated within first and second slots 260 to install pleated air filter 400 in lower base 210. With this done, upper cover 110 can be brought into position and attached to lower base 210 to provide a framed air filter 1. The seating of securing tabs 501 of opposing primary ends 402 of pleated air filter 400 into upward-open-ended elongate slots 260 of frame 10 can allow the pleated air filter to be held in place on the frame, in spite of any force that is exerted on the air filter by the impinging of flowing air on the upstream surface of the air filter. In at least some embodiments, this can be achieved without having to use any additional attachment methods such as adhesively bonding the reinforced end pleat-panels to the frame, or, in general, without adhesively bonding or mechanically fastening (such as with staples) any portion of the air filter to any portion of the frame.

[0103] In some instances, a slot 260 may comprise features that increase the tightness with which a securing tab 501 of a pleated air filter 400 is held in the slot. In some embodiments, such features may be provided in the form of ribs that extend outwardly from an inward primary sidewall that inwardly defines the slot, and / or ribs that extend inwardly from an outward primary sidewall that outwardly defines the slot. In some embodiments, such ribs may be tapered, meaning that they are narrower toward the open end of the slot (and may disappear completely near the open end) and protrude further into the interior of the slot (along a generally inward-outward direction of the frame portion) toward the bottom of the slot. Such arrangements can provide that as a securing tab of an air filter is pushed more deeply into the slot, the pleatpanel is held more and more tightly, which may provide useful haptic feedback to an end-user as to whether the securing tab is fully seated in the slot. Such arrangements are disclosed in detail e.g. in U.S. Provisional Patent Applications 63 / 607966 and 63 / 684727 and in U.S. Publ. No. 2025-0186922 resulting therefrom, all of which are incorporated by reference herein in their entirety. As disclosed herein, a pleated air filter 400 can be installed into lower base 210 so that the securing tabs 501 of the air filter are seated in elongate slots 260 of the lower base. In practice, this may be easily done e.g. by placing lower base 210 on a horizontal surface (e.g. a tabletop or countertop) so that the open ends of slots 260 of lower base 210 face generally upward, positioning pleated air filter 400 within the partial-cavity defined by lower base 210, and securing pleated air filter 400 on lower base 210 by inserting the first and second securing tabs 501 generally downward into the corresponding first and second elongate slots 260 of the lower base. According to this terminology, upper cover 110 will comprise an upward side 115 and a downward side 116 and lower base 210 will comprise an upward side 215 and a downward side 216 as indicated in FIGS. 3 and 4; the resulting frame 10 will comprise an upward side 15 and a downward side 16 as indicated in FIG. 2; and, framed air filter 1 will comprise an upward side 5 and a downward side 6 as indicated in FIG. 1.

[0104] As noted earlier, the above-described mode of installation is the basis for the terminology of “upward” and “downward” directions as used herein. However, again as noted earlier, this terminology is used for convenience of description and does not limit the orientation that the various items can be placed in. (For example, in some instances a lower base might be placed so that it stands vertically, end-wise, on a horizontal tabletop, with an air filter being inserted into the lower base while the lower base is in this vertical orientation.) With pleated air filter 400 installed in lower base 210 (however achieved), upper cover 110 can then be moved (e.g. vertically lowered) into position on lower base 210. Upper cover 110 and lower base 210 can then be attached to each other, e.g. with a system of latches 171 and 271 as noted earlier herein.

[0105] A framed air filter 1 as disclosed herein can be inserted into a suitable receptable of a powered airhandling apparatus (or equivalently, system). The term powered air-handling apparatus encompasses, among others, room air purifiers and forced-air heating-ventilating-air-conditioning (HVAC) systems. In this context, the term HVAC broadly encompasses systems that perform only heating, systems that perform only cooling, and systems that perform both (of course, such systems can be operated to recirculate and filter air, even if the system is neither heating or cooling at the time). The framed air filter can be inserted and removed by any end-user; an end-user does not necessarily have to be an occupant (e.g. a homeowner or renter) of a dwelling. Rather, in many instances an end-user may be an HVAC service technician, a custodial or maintenance worker at a facility, and so on.

[0106] In many embodiments, a framed air filter 1 may be installed in a receptacle of a powered airhandling apparatus so that the “upward” side 5 of the framed air fdter, per the terminology introduced earlier herein, is the “upstream” side of the framed air filter (that is, the side against which the incoming airstream impinges). Likewise, the “downward” side 6 of the framed air filter will be the “downstream” side (through which the filtered air exits the filter). Discussions so far herein have focused on arrangements of this type; such arrangements are referred to herein as a framed air filter being installed in an powered air-handling receptacle in a “standard” configuration. However, in some embodiments, a framed air filter can be installed in a receptacle in a “reverse” configuration; that is, with the “upstream” side of the framed air filter as installed in receptacle of a powered air-handling apparatus, being the “downward” side of the framed air filter, and the “downstream” side of the framed air filter as installed in receptacle of a powered air-handling apparatus, being the “upward” side of the framed air filter. The present investigations have revealed that in some embodiments, serviceable air filtration can still be obtained when a framed air filter is installed in such a reverse configuration. In such a case, not all of the herein-described performance enhancements may necessarily be achieved in their entirety (e.g., the “downstream” side of the frame may not abut against flanges of the filter-holding fixture so as to substantially eliminate any air from bypassing around the outside of the frame, as completely as might be the case with standard installation, in which a sealing apron is abutted against the flanges of the filter-holding fixture). However, such reverse installations are encompassed within the concepts disclosed herein. Thus for example, in some embodiments a framed air filter as disclosed herein may provide satisfactory air-filtration even if a user inadvertently installs the framed air filter in a reverse configuration. Indeed, in some embodiments a framed air filter may be designated (e.g., in signage and / or in user instructions) as reversible, so that the framed air filter may be installed in either standard or reverse orientation.

[0107] At a desired time (e.g. if it is considered that the air filter is approaching the end of its useful life) the framed air filter 1 can be removed from the receptable of the powered air-handling apparatus (noting that the previously -described handles 161 can facilitate this). The latches 171 of upper cover 110 can be momentarily deflected outward to free them from complementary latches 271 of lower base 210, and upper cover 110 can then be separated from lower base 210. The first and second ends of 402 of pleated air filter 400 can then be manipulated (e.g., while grasping the pleated air fdter 400 by handles 506) to remove the securing tabs 501 of the spent pleated air filter 400 from the elongate slots of the lower base. The spent air filter 400 can then be removed from the lower base and recycled, discarded, etc. A fresh pleated air filter 400 can be expanded to an in-use condition (e.g. ifthe fresh air filter was supplied in a compacted condition) and installed in lower base 210. Upper cover 110 can then be re-attached to lower base 210 and the resulting framed air filter 1 can then be re-inserted into the filter-receptacle of the powered air-handling apparatus.

[0108] In some embodiments, at least one air filter (e.g. pleatpack) 400 and / or a reusable frame 10 may be provided as part of a kit, in any suitable format. For example, a starter kit may comprise a lower base 210 and a upper cover 110 along with at least one compacted pleatpack 400. In a convenient embodiment, in such a kit, the lower base and upper cover may already be mated to form frame 10, with several compacted pleatpacks 400 being packaged side-by-side (in the expansion direction Deof the pleatpacks) in the filterreceiving cavity 30 of the frame (since the cavity may be large enough to hold several fully -compacted pleatpacks). An end user can separate the upper cover and lower base, remove the pleatpacks, and install one pleatpack into the frame in an expanded, in-use condition. Since frame 10 is reusable so that it can be used repeatedly over a long period of time, air filters 400 may also be available in the form of replacement filter packs that include e.g. one, or multiple, collapsed pleatpacks, without any frame.

[0109] It will be apparent to those skilled in the art that the specific exemplary embodiments, elements, structures, features, details, arrangements, configurations, etc., that are disclosed herein can be modified and / or combined in numerous ways. In summary, numerous variations and combinations are contemplated as being within the bounds of the conceived invention, not merely those representative designs that were chosen to serve as exemplary illustrations. Thus, the scope of the present invention should not be limited to the specific illustrative structures described herein, but rather extends at least to the structures described by the language of the claims, and the equivalents of those structures. Any of the elements that are positively recited in this specification as alternatives may be explicitly included in the claims or excluded from the claims, in any combination as desired. Any of the elements or combinations of elements that are recited in this specification in open-ended language (e.g., comprise and derivatives thereof), are considered to additionally be recited in closed-ended language (e.g., consist and derivatives thereof) and in partially closed-ended language (e.g., consist essentially, and derivatives thereof). Although various theories and possible mechanisms may have been discussed herein, in no event should such discussions serve to limit the claimable subject matter. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document that is incorporated by reference herein but to which no priority is claimed, this specification as written will control.

Claims

What is claimed is:

1. A reusable rectangular outwardly tapered channel frame configured to receive a pleated air filter, the frame comprising: first and second opposing primary frame portions and first and second opposing secondary frame portions, the primary and secondary frame portions meeting at comers of the rectangular frame and each of the frame portions comprising an outer sidewall and an upper flange and a lower flange, wherein for all of the frame portions, at least the upper flange is sloped so that the frame portion is outwardly tapered so as to exhibit an outward taper ratio of from 0.95 to 0.60.

2. The frame of claim 1 wherein for each of the frame portions, the upper flange exhibits an inwardly- decreasing slope with an outermost slope angle of from 25 degrees to 80 degrees, and with an innermost slope angle of from 5 degrees to 20 degrees.

3. The frame of claim 1 wherein for each of the frame portions, the upper flange exhibits a compound taper provided by an outward sloped section that is highly sloped and an inward sloped section that is moderately sloped, and wherein for each of the frame portions, the lower flange exhibits a single taper provided by an outward sloped section that is highly sloped, with the proviso that the lower flange does not comprise a moderately-sloped inward sloped section.

4. The frame of claim 3 wherein the highly -sloped outward sloped section of the upper flange, and the highly-sloped outward sloped section of the lower flange, each comprise a slope angle of from 30 to 65 degrees, and wherein the moderately-sloped inward sloped section of the upper flange comprises a slope angle from 10 to 20 degrees.

5. The frame of claim 3 wherein a span of the moderately-sloped inward sloped section of the upper flange is from five to twenty times a span of the highly-sloped outward sloped section of the upper flange.

6. The frame of claim 3 wherein the highly-sloped outward sloped section of the upper flange and the moderately-sloped inward sloped section of the upper flange meet at an integral junction, and wherein the upper flange comprises a substantially-unsloped inwardmost section that extends integrally inward from the moderately-sloped inward sloped section of the upper flange.

7. The frame of claim 1 wherein the frame is a two-piece frame assembled by mating a rectangular upper cover to a rectangular lower base and detachably latching the upper cover to the lower base with one or more integral latches, wherein the upper cover defines an upper window and the lower base defines alower window, wherein the upper cover provides the upper flange of each frame portion and the outer sidewall of each frame portion, and wherein the lower base provides the lower flange of each frame portion.

8. The frame of claim 7 wherein in at least some parts of each frame portion, a lowermost terminus of the outer sidewall of the upper flange is abutted against an upward-facing surface of a lower lip of the lower flange, and wherein an outwardmost region of the lower lip of the lower flange comprises a highly- sloped outward sloped section of the lower flange.

9. The frame of claim 8 wherein the lower lip of the lower flange extends generally around the entirety of a perimeter of the lower base, and wherein a lowermost, downward-facing surface of the lower lip is at least substantially planar along an entire extent of the lower lip so as to provide a planar sealing apron.

10. The frame of claim 7 wherein the upper cover comprises first and second opposing primary cover portions and first and second opposing secondary cover portions, the primary and secondary cover portions meeting at comers of the upper cover; wherein the lower base comprises first and second opposing primary base portions and first and second opposing secondary base portions, the primary and secondary base portions meeting at comers of the lower base; and wherein comer of the upper cover provides an outer sidewall of the frame at a comer of the frame, and wherein at each comers of the frame, the outer sidewall is arcuate with a radius of curvature of from one to three cm.

11. The frame of claim 10 wherein the lower base comprises a primary axis and a secondary axis; wherein the lower base comprises a set of lower stmts that extend from a primary base portion to an opposing primary base portion and / or from a primary base portion to a secondary base portion and that cross the lower window defined by the lower base; and wherein within a central 50 % of the area of the lower filtration window, the stmts of the set of lower stmts are oriented at an off-angle of from 35 degrees to 75 degrees relative to the primary axis of the lower base.

12. The frame of claim 10 wherein each of the first and second opposing primary cover portions and each of the first and second opposing secondary cover portions of the upper cover, comprises at least one handle that is located within an inward recess provided in an outer sidewall of the cover portion, the handle comprising a T-shaped member with an inward shank and with an outward flange.

13. The frame of claim 10 wherein at least one cover portion of the upper cover, and at least one corresponding base portion of the lower base, each comprise at least one complementary detent feature configured to hold the cover portion and the corresponding base portion together, with the at least one complementary detent feature of the cover portion being inward-facing and with the corresponding baseportion comprising at least one integral bollard that, as the cover portion and the corresponding base portion are mated together, urges the cover portion inwardly to facilitate the complementary detent features’ holding the cover portion and the corresponding base portion together.

14. A method of installing a pleated air filter in the frame of claim 1 to form a framed air filter, the method comprising: inserting a first securing tab of a first primary end of the pleated air filter into a first upward-open- ended elongate slot of a first primary portion of the lower base; inserting a second securing tab of a second, opposing primary end of the pleated air filter into a second upward-open-ended elongate slot of a second, opposing primary portion of the lower base, so that the pleated air filter is installed in the lower base; then, detachably attaching the upper cover to the lower base to form the framed air filter comprising the reusable frame with the pleated air filter installed therein.

15. The method of claim 14 wherein the method includes a further step of installing the framed air filter in a framed-filter-receiving receptacle of a powered air-handling apparatus chosen from the group consisting of an HVAC system and a room air purifier, wherein the installing is performed by slidably inserting the framed air filter along a primary axis of the framed air filter or along a secondary axis of the framed air filter, into a framed-air-filter-receiving slot of the HVAC system.

16. The method of claim 14 wherein the first upward-open-ended elongate slot of the first primary portion of the lower base and a first moderately-sloped inward sloped section of a first primary portion of the upper cover, are configured so that when the pleated air filter is installed in the frame with the first securing tab of the first primary end of the pleated air filter seated in the first upward-open-ended elongate slot of the first primary portion of the lower base, the first moderately-sloped inward sloped section of the first primary portion of the upper cover does not contact any upper pleat tip of the pleated air filter.

17. The method of claim 14 wherein a first reinforcing sheet is mounted on a first end pleat-panel of the pleated air filter to provide the first securing tab in the form of a reinforced end pleat-panel of the pleated air filter, the reinforcing sheet comprising an inward segment that is attached, directly or indirectly, to an inward face of the end pleat-panel, and an outward segment that is attached to an outward face of the end pleat-panel, the inward and outward segments of the reinforcing sheet integrally meeting at a downward apex located downward of a downward tip of the end pleat-panel.

18. The method of claim 17 wherein the first reinforcing sheet further comprises a handle segment that extends integrally from an integral, hinged connection of the handle segment with an upper end of the outward segment of the first reinforcing sheet, with the handle segment not being attached to the first end pleat-panel; and wherein the method further includes a step of, after the pleated air filter is installed in the lower base, folding the handle segment inwardly so that the folded handle segment upwardly overlies an upper pleat tip of the first end pleat-panel of the pleated air filter, so that after the upper cover is attached to the lower base, at least a portion of the inwardly -folded handle segment is positioned between an upper side of the pleated air filter and a substantially -unsloped inwardmost section of the first primary portion of the upper cover.

19. The method of claim 17 wherein when the pleated air filter is installed in the lower base, a first corrugated edge of the pleated air filter is abutted against an inward surface of a first inner secondary sidewall of a first secondary portion of the lower base; and, wherein the first inner secondary sidewall of the first secondary portion of the lower base is inwardly positioned relative to a moderately-sloped inward sloped section of a first secondary portion of the upper cover, so that in the framed air filter, the moderately- sloped inward section of the first secondary portion of the upper cover does not impinge on the first corrugated edge of the pleated air filter.

20. The method of claim 19 wherein the first secondary portion of the upper cover comprises a substantially-unsloped inwardmost section that extends integrally inward from the moderately-sloped inward section of the first secondary portion of the upper cover, the first secondary portion of the upper cover and the first secondary portion of the lower base being configured so that in the framed air filter, the substantially -unsloped inwardmost section of the first secondary end of the upper cover overlies the first corrugated edge of the pleated air filter and a first corrugated edge area of the pleated air filter.

21. The method of claim 14 wherein in the framed air filter, the pleated air filter resides in an air-filter- receiving cavity comprising a central area whose depth is defined by a distance between lower surfaces of upper struts of the upper cover and upper surfaces of lower struts of the lower base, and wherein the upper cover, the lower base, and the pleated air filter are configured so that the depth of the central area of the airfilter receiving cavity is from 90 to 99 % of a pleat height of the pleated air filter.

22. A kit comprising the frame of claim 1, the frame comprising a lower base and an upper cover that, as provided in the kit, are detachably attached to each other to form the frame, the kit further comprising at least two pleated air filters, each pleated air filter being in a compacted condition and with the at least two pleated air filters being disposed in a side-by-side manner along a secondary axis of the frame, within a pleated-air-filter-receiving cavity defined within the frame.

23. A framed air filter comprising the frame of claim 1 and a pleated air filter removably installed in the frame.

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